1. Field of the Invention
The invention relates to a cable assembly, and particularly to a ground plane cable assembly utilizing a flat ribbon cable.
2. The Prior Art
Historically, cable assemblies and connectors within a computer transfer data at speed, which do not readily lead to signal degradation due to electromagnetic phenomenon such as impedance, skew, propagation delay, and crosstalk. As signal speed continues to increase, however, these phenomena can create sever problems within the computer system. An effort is therefore being made to control various electrical characteristics of cable assemblies and associated connectors within the computer enclosure.
The well known technology for avoiding aforementioned signal degradation is to use a ground plane associated with the traditional flat ribbon cable wherein the ground plane directly abuts against the flat cable. Anyhow, in such design, the impedance can not be raised to a desired level during a high speed transmission. Therefore, based on a theory that the impedance is of inverse proportion to the capacitance, it is required to have a dielectric layer positioned between the ribbon flat cable and the ground plane for reducing the capacitance. Moreover, due to the limited properties of such dielectric layer, generally such dielectric layer should maintain a significant thickness to obtain a required lower level of the capacitance. It will result in a heavy and thicker cable assembly. Thus, it is further desired to modify such dielectric layer for maintaining a thinner thickness while still providing the desired lower level of the corresponding capacitance between the conductors of the flat ribbon cable and the ground plane.
Therefore, an object of the invention is to provide a ground plane cable assembly utilizing a flat ribbon cable wherein the capacitance between flat ribbon cable and the ground plane reaches a relative low level in comparison with the prior art.